Compensatory growth following various time lengths of restricted feeding in rainbow trout (Oncorhynchus mykiss) under summer conditions



This study was conducted to determine the effects of various time lengths of restricted feeding at 0.5% of body weight on compensatory growth (CG) in rainbow trout under summer conditions. Seven treatments with triplicate tanks consisted of control (C) fed to satiation over 98 days and the remainder being one (R1) to six (R6) weeks of restriction and then refeeding for the remaining 8 weeks of the experiment. At the end of the experiment R1 and R2 were able to catch up with C. Repeated measures anova suggested a convergence in body mass but not in body length (structure), whereas there was an association between mass and structural CG responses. Hyperphagia and transiently better food utilisation were main mechanisms of the observed CG. Organosomatic indices of the restricted groups were significantly reduced at the end of the restriction periods, but were restored to the control fish levels by the end of the refeeding period. There was a linear increase in body moisture and a decrease in lipid and lipid/lean body mass ratio with the severity of the restriction periods, but these trends vanished by the end of refeeding. The findings of the present experiment suggest that restricted feeding and the following realimentation to elicit CG as a management tool can be used in rainbow trout, but for no more than 2 weeks under summer conditions.